WASHINGTON — In a stinging rebuke of the military’s efforts to curb sexual assault, members of a Senate panel hammered Defense Department officials Wednesday for making too little progress in combating the crimes and failing to improve a military justice system that victims described as slow and uncaring.

During a two-part hearing, the panel heard harrowing testimony from several victims, who said military justice is broken and pushed for Congress to take action to stem the rape, sexual assault and sexual harassment that they said are pervasive in all the service branches.

Pentagon officials said they are taking the problem seriously. “Sexual assault in the military is not only an abhorrent crime that does enormous harm to the victim, but it is also a virulent attack on the discipline and good order on which military cohesion depends,” said Robert Taylor, the Pentagon’s acting general counsel.

“The Air Force has zero tolerance for this offense,” added Lt. Gen. Richard Harding, the judge advocate general of the Air Force.

But lawmakers pointed to a decision by Air Force Lt. Gen. Craig Franklin to reverse a guilty verdict in a sexual assault case as evidence of how the military fails the victims who come forward to report the crimes.

Under military law, a commander who convenes a court martial is known as the convening authority and has the sole discretion to reduce or set aside guilty verdicts and sentences or to reverse a jury’s verdict.

Her voice rising, Sen. Kirsten Gillibrand, D-N.Y., said all the promises of “zero tolerance” from the witnesses amount to nothing if a convening authority is the only individual who can decide whether to overturn a case. Gillibrand is the chairwoman of the Senate Armed Services Personnel Subcommittee.

“I appreciate the work you’re doing, but it’s not enough,” she told the military officers arrayed at a long witness table.

Gillibrand then directed her frustration at Harding, demanding to know whether justice was done when Franklin overturned a military jury’s conviction. Harding responded that Franklin reviewed the facts and made an independent decision with integrity.

Gillibrand then asked whether justice was served when the five senior officers who made up the jury rendered a guilty verdict. Harding said he could not say.

“The jury and the convening authority did their duty,” he said.

Pointing out that they came to opposite decisions, Gillibrand pressed Harding on whether justice was done.

“I’m not going to conclude that justice was or was not done. All parties did what they were asked to do,” he said.

“One of the parties was wrong,” Gillibrand told him, adding that the female victim in the case does not believe justice was done.

Rebekah Havrilla, a former Army sergeant, told the panel that she encountered a “broken” military criminal justice system after she was raped by another service member while serving in Afghanistan. Havrilla described suffering from post-traumatic stress disorder and described how her case was eventually closed after senior commanders decided not to pursue charges.

“What we need is a military with a fair and impartial criminal justice system, one that is run by professional and legal experts, not unit commanders,” Havrilla said.

BriGette McCoy, a former Army specialist and a Persian Gulf war veteran, said she was raped when she was 18 and at her first duty station. But she did not report it. Three years later, she reported being sexually harassed and asked for an apology and to be removed from working directly with the offender.

“They did remove me from his team and his formal apology consisted of him driving by me on base and saying ‘sorry’ out of his open car door window,” McCoy told the subcommittee.